title: Liquid chromatographic determination of cephapirin residues in milk.
abstract: A liquid chromatographic (LC) method was developed for quantitative determination of cephapirin residues in milk that also resolved cephapirin from ampicillin, cloxacillin, and penicillin G. Diluted milk was passed through a C18 cartridge on which the cephapirin was adsorbed; then, interfering material was removed by washing with water and methylene chloride and cephapirin residues were eluted with methanol-acetonitrile (25 + 75). After drying, residues were dissolved in the mobile phase for injection. The LC system had an ultrasphere-ODS column with RP-18 Spheri-10 guard column and a UV detector with a 254 nm filter. The mobile phase was 85% sodium acetate (0.01M) and 15% methanol-acetonitrile (25 + 75) with a flow rate of 1 mL/min. Sensitivity was 20 ppb or less with a recovery of 61-80% in the range studied. Other beta-lactam antibiotics tested did not interfere with detection of cephapirin. Analysis of 30 samples of commercial homogenized milk obtained for a survey of antibiotics in consumer milk in Canada revealed no detectable cephapirin residues.
authors.affiliation: Health and Welfare Canada, Bureau of Drug Research, Tunney's Pasture, Ottawa, Ontario, Canada.
authors.forename: A I
authors.initials: AI
authors.lastname: MacIntosh
mesh_terms: D000818:Animals; D002514:Cephapirin / Q000032:analysis*; D002853:Chromatography, Liquid; D004350:Drug Residues / Q000032:analysis*; D005506:Food Contamination / Q000032:analysis*; D008892:Milk / Q000737:chemistry*
chemical_list: D002514:Cephapirin